For the X3, I was thinking that when left unlocked, the sleep system does activate but only after some period of time (not a clear cut interval, but maybe 20 mins. or so, similar to the timeout for the radio).

At that point, the only noticeable thing drawing power is the little orange light for the A/T shift position. (Not sure of the purpose of that staying on.)

If something like the overhead light had been left on, this seems to get turned off when the sleep system takes over (but will go back on again next restart).

If you lock the doors, the sleep system might activate immediately, that A/T light goes out, and the clown nose starts flashing.

In my case, with no options, and no electronic accessories, battery depletion when sitting either locked or unlocked for a week or more hasn't been an issue.

So I would surmise that the current draw from the clown's nose (and immobilizer) is not much different from that for the little A/T light...

It might go into 'sleep' mode after a specified period of time; I was kind-of extrapolating my own observations and experiences with the C5 Corvette to the X3, which may or may not apply. It all boils down to how BMW set up the ECU logic for 'sleep' mode in the X3.

But I'm not sure the 'battery saver' feature (which turns off lights after a period of time to prevent battery discharge; the C5 also has that feature) is quite the same as 'sleep' mode. They may act independently of one another, and key on different 'triggers' to activate.

The A/T light and 'clown nose' indicator for the security system are both almost certainly LED's, which consume very little power. I have a dealer-installed ignition kill switch installed in my '97 GMC Jimmy that has an LED indicator light, and I've let that thing sit for a couple of weeks with it blinking away without even getting close to discharging the battery.

Quote:

Originally Posted by Supercourse

... Cigarette lighter outlets are outside the sleep system control, allowing a battery tender/minder to be connected there if you choose.
(Seems to be a European thing for always live outlets, Asian and domestic makes favor ignition-switched outlets.)

But that means, of course, that some other personal entertainment/productivity devices left unwittingly on can drain the battery.

I don't think that locking the X3 turns those 12V outlets off.

Quote:

Originally Posted by UncleJ

... my domestic cars and trucks all have live lighter sockets when the key is "off".

These could be a source of draw on the battery, but only if something (e.g., a cell phone or iPod charger) is continuously plugged into it during those extended idle periods.

Even if the 12-volt outlets are 'live' when the car is shut off, when nothing is plugged into it, there's nothing to complete an electrical circuit; and therefore, no draw on the battery.